I am developing a router milling head for the NM-200. It would allow a Porter Cable 2-1/4 HP Variable Speed 3.5" body diameter router to be mounted in place of the stock milling head for use in woodworking and with small metal-cutting bits.

The NM-200 has a top spindle speed of 3000-4000 RPM and tends to generate a lot of heat in the spindle bearings at higher speeds. The NM-135 has a top speed of 6000 RPM. Small metal bits and wood routing bits require higher RPM for the optimal speeds and feeds. With the attachment, speeds would be possible in the 10,000 to 27,000 RPM range.

The target user of this attachment would be someone like myself who needs to cut some heavy duty projects at lower speeds with the stock head, but also occasionally machines wood or uses small metal-cutting bits such as 0.125" or smaller. This attachment would increase spindle speeds to allow greater feed rates and more efficient machining.

I am building one unit for myself, but wanted to see if anyone else had interest in this type of attachment.

I would be interested in working with someone who has an NM-135. My own machine is an NM-200, and was hoping to make one for the NM-135 as well. I would need information on how such an attachment could be installed on a 135. The attachment for the NM-200 would replace the entire milling head where it attaches at the circular mounting plate with the existing 2 bolts.

I would be willing to share my CAD designs with an individual wanting to work with me on a 135 version, as well as perhaps build an attachment for them to test and keep when done.

So feel free to contact me if you have interest in one (or more) of the following:
A) Working with me to develop the attachment for the 135.
B) Purchasing a ready made attachment for the NM-135 or NM-200
C) Purchasing plans (and maybe even the GCode) for building the attachment.

THIS IS NOT an advertisement, there is nothing actually for sale at this point, just seeing how much interest there is in the attachment and/or plans.

Thanks! You can reply here, private message me, or my email is cjones@cjjonesarmory.com

I've ordered a Macro Tech air spindle, good for 30krpm, and fits into my NM135 existing spindle.

http://www.macrotechnologies.com/high_speed_air_spindle_mini_mac.htm

This kind of spindle has very little power compared to your 2HP router, but I need the RPMs for engraving.

I thought alot about rigging a router (I even bought the Bosch 1HP laminate trimmer); one of the main problems is bolting the bosch to the side of the millhead would result in a 4" or 5" offset between the NM135's spindlecenter and the bosch spindlecenter - and a bigger router would be even more than 5".

After I bought the macro spindle, I found this: TB-350S spindle from "Wolfgang Engineering" on ebay - half the price, 20krpm (although I'm sure you could coax it to 30k), doesn't require a compressor, unbelieveably good TIR. I'd have to build an NM135 mount for it, but it is short enough, and the NM135's Z-travel is tall enough, that I could probably mount it directly under the NM135's spindle. And again, this is a low-power spindle.



With regards to your "NM200 spindle produces alot of heat in the bearings"... my NM135 did the same, but is has gotten _alot_ better after a few hours of run-in. (I plugged the mill into the wall through a wattmeter, so I can see the exact powerdraw). It now runs cooler to the touch, and draws alot less power than when it was new. Definitely better with age.

Further, once the spindle warms up, the powerdraw drops alot.

In case your not busy enough, here's another project you might want to consider: Novakon tap attachment. Just like Hoss's:

http://www.hossmachine.info/projects_8.html

This is something I'd be willing to pay money for. Totally useful, totally simple. The NM135 (and NM200 too??) already has the 4th axis ready to drive the stepper.

Here is the first version of the router attachment. I was concerned the setup would be flimsy without being welded, but the bolted version works extremely well and is rock solid. If I were to produce this for sale, I would probably weld the parts.

The router clamp needs a bit of refinement. I did not have a way to make a router clamping system like the original router base clamp. I want a springy clamp system that "grasps" the router rather than the bolt-together system. I had to carefully fit shims between the clamp halves to get the proper hold, not something that is user friendly, and could potentially damage the router if not done properly.

http://www.cnczone.com/gallery/data/500/medium/IMG_8396_Small.jpg

In case your not busy enough, here's another project you might want to consider: Novakon tap attachment. Just like Hoss's:

http://www.hossmachine.info/projects_8.html

This is something I'd be willing to pay money for. Totally useful, totally simple. The NM135 (and NM200 too??) already has the 4th axis ready to drive the stepper.


Doing the tapping attachment sounds like a good plan. I've already been experimenting (or at least researching) what I would need to do to get a positive RPM feedback from the existing spindle.

The VFD is controlled by Mach3 (through the C11G board from CNC4PC) by the 0-10VDC signal, but it's not exactly accurate. Ok, it's nowhere near accurate even with extensive tuning. It can be off by as much as a couple hundred RPM in some RPM ranges. WHen using the C11G board, Mach3 is configured to use step and direction pulses, the C11G board converts that to a 0-10VDC signal. The upper range of the signal is adjusted with a "pot" on the board itself. The VFD then interprets the 0-10VDC signal into an RPM. The VFD is very configurable as there are low-limits, high-limits, acceleration curves, etc... all configurable in the VFD. Very useful, but it seems like there is a more accurate way to control the spindle.

The VFD has the option to be PID controlled, and Mach3 has the option to use PID control. I just haven't been able to figure out exactly what I need to get Mach3 and the VFD to communicate. Most of the trouble comes from the VFD's interpreted instruction manual. It's not to read well ;) (if you catch my meaning). I believe that using the RS485 port on the VFD is the key, but I've been too busy to mess with something to interface the RS485 port and the PC. Sunfar sent me a copy of their PC Control Software, but it crashes and won't run. It was missing a dll or some other file needed. I really should ask them if they have an updated version.

Alternately, I was trying to figure out if there was a way to attach a sensor to the spindle that would provide a positive feedback to Mach3 to be able to fine tune the spindle RPM, again, no time for research.

Anyway, if I could get 100% accurate RPM, then tapping would be easy to do with the existing spindle.

As a final alternative, (perhaps the most expensive alternative) is to buy or build a reversing tapping head, but there are problems there too.

Back to the issue, maybe if people reading this thread see an image of the router attachment, they may be more interested. I am extremely happy with it's operation so far. The next step up would be to make an actual high speed spindle instead of the router. The prices of the aftermarket high speed spindles are much too high. I expect the router to live for quite a while, but it really isn't designed for hours and hours of continuous operation at speeds and forces that humans probably would not exert.

Doing the tapping attachment sounds like a good plan. I've already been experimenting (or at least researching) what I would need to do to get a positive RPM feedback from the existing spindle.


To be honest, I firmly believe that tapping using the existing spindle motor is completely hopeless - you'd need impossibly-precise RPM feedback sampled at an impossibly-fast rate. The only way would be a hall sensor directly on the shaft of the motor, driving dedicated HARDWARE, which directly pulses the Z-stepper; Sluggish Windowz cannot be involved. Essentially, what you need to know is the spindle's angular position, not RPMs. In mathematical terms, when tapping, the Z-height is directly proportional to spindle angle - easy and perfectly accurate with steppers; if you want to make Z-height a function of RPMs instead, Z height is the integral of RPMs over time. And in integration, all error will be cumulative - 'tis hopeless.
Plus, the spindle almost certainly has inadequate (on the NM135, at least) torque at the low RPMs needed for tapping - indeed, my spindle won't even spin below 500rpm, cuz it ain't designed to. Anyhoo...

FYI - Novakon sells cheap steppers that look like they'd do the job. Add a plate of aluminum, two cogs and a belt, and we're done....

Back to the issue, maybe if people reading this thread see an image of the router attachment, they may be more interested. I am extremely happy with it's operation so far. The next step up would be to make an actual high speed spindle instead of the router. The prices of the aftermarket high speed spindles are much too high. I expect the router to live for quite a while, but it really isn't designed for hours and hours of continuous operation at speeds and forces that humans probably would not exert.

That looks like a pretty solid jig. The one drawback that comes to mind though is the thought of removing a 100lb milling head every time I want to use the router. And putting it back on.

If I had the NM200, and wanted more RPMs (6000, say), I'd consider the following: ask Novakon how much a replacement spindle costs, and if it's reasonable, order one as a spare, and change out your belt/cog ratio to give you 6k. If you cook the bearings, then you're out the cost of the spare. If you don't cook the bearings, then you've got a 6k setup (albeit at proportionally lower torque - but the NM200's motor is fairly beefy, so that shouldn't be a problem).

The one drawback that comes to mind though is the thought of removing a 100lb milling head every time I want to use the router. And putting it back on.

Yeah, it's a pain. I've been using an engine hoist to do the trick lately, but I plan on using a gantry hoist setup with electric hoist and a trolley. I does definitely require you to plan the projects ahead of time. On the other side of the issue though, assuming my engine hoist is in position, it takes only about 20 minutes to change heads. I have installed quick connects on the electrical components of the standard milling head. To change it, just remove two bolts, disconnect two connectors and the head is off.

To install the router assembly, connect up one of the quick electrical connections (the one with the E-stop), and install two bolts to hold it in place. The router power cord routes alongside the other wiring and plugs in to a standard outlet. No auto-on/off, but it's not that hard to remember. I suppose I could put a relay in there, but it's not a big deal to me right now.

If I had the NM200, and wanted more RPMs (6000, say), I'd consider the following: ask Novakon how much a replacement spindle costs, and if it's reasonable, order one as a spare, and change out your belt/cog ratio to give you 6k. If you cook the bearings, then you're out the cost of the spare. If you don't cook the bearings, then you've got a 6k setup (albeit at proportionally lower torque - but the NM200's motor is fairly beefy, so that shouldn't be a problem).

I have already had one set of bearings go out, and that was in the "normal" rpm range. I have other posts on this issue, but basically, the bearings already got cooked once (I think it was contamination in the bearing from the factory). And at only 3100 RPM, the milling head is already at 150-160 Deg F. I don't think it'd live at anything higher.